2-aralkyl derivatives of delta4-pregnene-3, 20-dione and process for their production



United States PatetItO 2,947,762 Z-ARALKYL DERIVATIVES F A -PREGNENE-3,20-

DIONE AND PROCESS FOR THEIR PRODUC! TION n Howard J. Ringold and George Rosenkranz, Mexico City, Mexico, assignors to Syntex S.A., Mexico City, Mexico, a corporation of Mexico No Drawing. 'Filed Jan. 29, 1957, Ser. No. 636,858

Claims priority, application Mexico Jan. 31, 1956 4 Claims. (Cl. 260-3973) The present invention relates to novel cyclopentanophenanthrene derivatives and to a novel process for the production thereof.

More particularly the present invention relates to novel 2-alkyl and 'aralkyl derivatives of A -pregnene- 3, 20-dione which may be further substituted by hydroxy.

or acyloxy groups at positions C-17v and/or C-21 of the steroid molecule; as in the compounds 2-a1kyl or aralkyl A pregnene 17oz ol 3,20 dione and 17 esters thereof, 2-alkyl or aralkyl-A -pregnene-21-o1-3,20 dione;

and 21-esters thereof, and 2-alky1 or aralkyl-A -pregnene-17a,21-dio1-3,ZO-dione, the 21-esters and the 170:,

invention are novel useful hormones having activities of the hormones of the cortical type. In addition all of the novel compounds of the present invention are valuable therapeutics for the inhibition of cardiac fibrilation.

lnflaccordance with the present invention it has been discovered that the 20-monoethyleneketals of A -pregnene-3,20-dione (progesterone), of A -pregnene-17a-ol- 3,20 dione (17-hydroxyprogesterone), of A -pregnene- 17a,2;l-diol-3,20dione (Reichsteins compound S), of A pregnene 21 ol 3,20 dione (11 desoxycorticosterone) upon treatment with ethyl formate in the presence of sodium hydride gives the corresponding 2- hydroxymethylene derivatives. These 'hydroxymethylene derivatives upon treatment with an alkyl or aralkyl iodide then give the corresponding 2-alkyl or 2-aralkyl- 2'-formyl derivatives which when subjected to the action of a mild basic medium such as alkaline activated alumina lose carbon monoxide to give the corresponding ZO-ethylene ketal of the desired 2-alkyl or 2-aralkyl compound. The ketal group can then be hydrolysed to the corresponding 20-ketone. The same compounds may also be prepared by treating the ZO-ethylene ketal ofthe 2-alkyl or aralkyl-2'-formyl compound with strong acid in methanol. Conventional esterification of these compounds gave the corresponding esters.

The novel compounds of the present invention may therefore be exemplified by the following formula:

2,947,762 A Patented Aug. 2, 1960 In the above formula R represents an alkyl group, preferably a lower alkyl group such as methyl, ethyl or propyl or R- may represent an aralkyl group such as benzyl. R. represents hydrogen, a hydroxy group or an acylate of the type conventionally found in esterified steroid alcohols, these-are generally those derived from hydrocarbon carboxylic acids of less than 12 carbon atoms such as acetic, propionic, cyclopentylpropionic, benzoic etc; R represents the same groups as R.

The novel compounds of the present invention may be prepared by a process exemplified by the following equation:

CHER

acid hydrolysis GHiR V In the above equation R represents the same group as heretofore set forth. R and R represent hydrogen or hydroxy. Y

The starting materials above designated are either known or may be easily and conventionally obtained from known compounds. Thus the. ZO-ethylene ketal of progesterone maybe obtained from pregnenolone by reaction with ethylene glycol followed by Oppenauer oxidation, the ZO-ethylene ketal of l7-hydroxyprogesterone may be obtained by the method of Juian et al. I.A.C.S. 72, 367 (1950),. the 20-ethylene ketal of A pregnene-17a,21-dio1-3,20-dione by the method of -Antonucci'et -al., J. Org.v Chem., 18, (l'950)', and the 1 20-ethylene, ketal of A -pregnene21-ol-3,20-dione by the method of Von Euw et al. Helv. Chim. Acta. 38,,

mixed with ethyl formats and sodium hydride. The reaction mixture is then stirred for a long period of time (of the order of 3 days) under a nitrogen atmosphere. Upon decomposition of the excess hydride and addition of ice. water two, layers were formed with the.

desired hydroxymethylene derivative in the aqueous layer in the form of its sodium salt. After separation of the aqueous layer, acidification and purification the desired, corresponding ZO-ethylene ketal of the Z-hydroxymethylene derivative was obtained.

The products of the step just described together with sodium hydride were suspended in an inert organic solvent such as benzene and treated with an. organic iodide, preferably a lower alkyl or aralkyl iodide such as methyl, ethyl, propyl' or benzyl iodide by heating or refluxing. for a prolonged period of time (of the order of 24 hours). Preferably the treatment was carried out under an atmosphere of nitrogen and after 24 hours additional iodide was added and refluxing continued for 48 additional hours. Additional iodide was then added and refluxing continued for a total time of the order of 72 hours- The reaction mixture was then cooled and washed with dilute base to remove unreacted starting material. After separation, evaporation of the organic layer and crystallization of the organic layer residue, the products were respectively, the ZO-ethylene ketals asamea layers were formed, of which the aqueous layer contained the hydroxymethylene derivative in the form of its sodium salt. The layers were separated and the aqueous layer was washed with ether and benzene, cooled to a temperature of 5 C. and acidified with an aqueous solution of ammonium chloride. The mixture was extracted with methylene chloride, the solution was evaporated to dryness under Vacuum and the residue was crystallized from acetone-hexane, thus giving 8 g. of the 20-ethylene-- ketal of Z-hydroxymethylene-progesterone.

Example 11 traces of unreacted starting material and the organic layer was evaporated to dryness under reduced pressure. The residue crystallized from acetone-hexane to give the 20- ethyleneketal of 2-methyl-2-formyl-A -pregnene-3,20-diof the 2-lower alkyl or benzyl-2-formyl-derivatives of M-pregnene-E,ZO-dione, or A -pfgH6n-17Ot-01-3,20-di0116 or A -pregnene-l7e,2l-diol-3,20-dione or A -pregnene-2lol-3,20dione.

The 2-lowcr alkyl or benzyl-2-formyl derivatives, thus prepared, were then treated with a mild base preferably activated alumina (chromatographic type) of alkaline reaction. This treatment involved passing a. benzene solution of the derivatives through a column of the alumina and after about a days time eluting the product from the column with an organic solvent suchas ethyl acetate. The products after crystallization were the ZO-ethylene ketals of the 2-lower alkyl or benzyl-derivatives of A pregnene-BQO-dione or A -pregnene-l7a-ol-3,ZO-dione, or A -pregnene-l7a, 2.l-diol-3,20-dione or A -pregnene-2l-ol- 3,2G-dione. The 20-ltetal group was then transformed to the 20-li8t0 group with a mineral acid in methanol to give the Zea-lower alkyl or benzyl final product.

Instead of the two step removal of CO' and hydrolysis of the ZO-ketal just described these transformations may be performed in a single step at lower yields by treating the 2-lower alltyl or benzyl-2'-for-myl compounds directly with a mineral acid such as sulfuric under reflux conditions for a short period of time.

The 2ct-lower alkyl or benzyl compounds were converted to esters having ester groupingsconventional in the steroid field by known methods of esterification. For producing 2l-esters of Zea-lower alkyl or benzyl derivatives of A -pregnene-l7a, 2l-diol-3,20-dione the free alcohols were treated with acid anhydrides in pyridine or with acyl halides. By this means there were prepared the types of esters heretofore set forth i.e. of hydrocarbon carboxylicacids of less than 12 carbon atoms. For the. esterification of the l7a-hydroxy group of a Zoc-lOWfir alkyl or benzyl-n -pregnene-17u-ol-3,20-dione the free compound was treated with acylating agents such as acid anhydrides in the presence of an acid such as P-toluenesulphonic acid.

The following specific examples serve to illustrate but are not intended to limit the present invention:

Example I A suspension of 10 g. of the ZO-monoethyleneketal of progresterone in 500 cc. of anhydrous benzene free of thiophene was mixed with 10 g. of ethyl formate and 3 g. of sodium hydride and the mixture was stirred for 3. days under an atmosphere of nitrogen. V The excess of hydride was decomposed by the cautious addition of 15 cc. of methanol, followed by 300' cc. of ice water; Two

one. This compound showed no color reaction with ferric chloride in aqueous ethanol even after standing for 24 hours.

1 g. of the above compound was dissolved in benzene and the solution was used to impregnate a column with; g. of alkaline activated alumina. After 24 hours the column was eluted with ethyl acetate and the combined eluates were crystallized from acetone-hexane to produce the ZO-ethylene-ketal of 2ot-methyl-progesterone.

1 g. of such 2(l-ethyleneketal was dissolved in 50 cc. of methanol containing 5 cc. of 8 aqueous sulfuric acid and the mixture was refluxed for 50 minutes, cooled and diluted with water. The methanol was removed by vacuum distillation, the residue was neutralized with sodium bicarbonate and extracted with chloroform. Crystallization afforded 2u-methyl-progesterone. I

Example III 1 g. of the ZO-ethyleneketal of Z-methyl-T-formyl-M- pregnene-3,20-dione was dissolved in 50 cc. of methanol containing an aqueoussolution of 8% sulfuric acid and the mixture was refluxed for 50 minutes. The cooled solution was diluted with Water, the methanol was removed by vacuum distillation and the residue was neutralized with sodium bicarbonate and extracted with chloroform. Crystallization yielded Za-methyl-progesterone, identical to the one obtained in accordance'with Example II.

Example IV 1 g. of the ZO-ethyleneketal of Z-hydroxymethyleneprogresterone was treated in accordance with the methoddescribed in Example ll, except that ethyl iodide was used instead of methyl iodide, thus giving 2m-ethyl-progesterone.

Example V 1 g. of the ZO-ethyleneketal of 2-hydroxymethylene-- progresterone was treated in accordance with the method described in Example II, except that propyl iodide was used instead of methyl iodide, thus giving 2a-propyl-pro-' gesterone.

Example VI A mixture of 2.2 g. of the ZO-ethyleneketal of 2-hydroxymethyleneprogesterone, mg. of sodium hydride, 50 cc. of benzene and 10 cc. of benzyl iodide was refluxed for 72 hours under an atmosphere of nitrogen. The cooled mixture was washed with previously cooled 1% sodium hydroxide solution and evaporated to dryness under reduced pressure. Crystallization from acetonehexane yielded the 20-ethyleneketal of 2-benzyl-2-formyl- A -pregnene-3,20-dione.

The treatment of the latter compound with alkaline The cooled mixture was;

activated alumina, followed or combined with a hydrolysis such as has been described in Examples II and III, afforded 2a-benzyl-progesterone.

Example VII g. of the ZO-ethyleneketal of 17-hydroxyprogcsterone was treated in accordance with the method described in Example II, thus giving 8 g. of the ZO-ethyleneketal of 2-hydroxymethylene-17-hydroxyprogesterone.

Example VIII 3 g. of the 20-cycloethyleneketal of 2-hydroxymethylene-l7-hydroxyprogesterone was treated in accordance with the method described in Examples II and III, thus Example IX 3 g. of the ZO-ethyleneketal of 2-hydroxymethylene-l7- hydroxyprogesterone was treated in accordance with the method described in the previous example, using ethyl iodide instead of methyl iodide, thus giving 2a-ethyl-l7- hydroxyprogesterone and its 17-esters.

' Example X 3 g. of the 20-ethyleneketa1 of 2-hydroxymethylene-17- hydroxyprogesterone was treated in accordance with the method described in Example VIII using propyl iodide instead of methyl iodide, thus producing 2a-propyl-17- hydroxyprogesterone and its 17-esters.

Example XI A mixture of 2.2 g. of the 20-ethyleneketal of 2- hydroxymethylene-l7-hydroxyprogesterone and 10 cc. of benzyl iodide was treated in accordance with the method described in Example VI, thus giving 20: benzyl 17- hydroxyprogesterone and its 17-esters.

' 6 Example XII '10 g. of the ZO-monoethyleneketal of Reichsteins Compound S was treated in accordance with the method described in Example II, thus yielding 8 g. of the ZO-ethyleneketal of 2 hydroxymethylene A -pregnene-17a,21-dio1- 3,20-dione.

3 g. of this compound was treated in accordance with the method described in Examples H and/or 111, thus giving 2a-methyl-A -pregnene-17a,21-diol-3,20-dione, from which we also prepared its 2l-acetate by routine acetylation with acetic anhydride in pyridine solution. Other esters of hydrocarbon carboxylic esters of less than 12 carbon atoms such as the propionate, cyclopentyl propionate and benzoate were similarly prepared by conventional reaction with acid :anhydrides and/or chlorides. The corresponding Za-ethyl, propyl, and benzyl derivatives were also similarly prepared.

Example X111 prepared. The corresponding Zoe-ethyl, propyl, and benzyl derivatives were also similarly prepared.

We claim:

1. 2a-benzyl-A -pregnene-3,ZO-dione.

2; Za-benzyl-A -pregnene-17a-ol-3,20-dione.

3. Za-benzyl-N-pregnene-Z1-ol-3,20-dione.

4. 2u-benzyl-A -pregnene-17a,21-diol-3,20-dione.

References Cited in the file of this patent Fieser et-a1.; Natural Products Related to Phenanthrene,

31 d. ed., pp. 301, 435 (1-949).

Chemical Abstracts, vol. 49 (1955), pars. 512 (i) Junkman et a1.

Hogg: J.A.C.S., 77, pages 6401-6402, Dec. 5, 1955. 

1. 2A-BENZYL-$4-PREGENE-3,20-DIONE. 